Scientific Notation & Sig Figs
Measurement & Units
Physical vs. Chemical Changes
Atomic Structure & Isotopes
Chemical Nomenclature & Formulas
100

The number 3.68 x 104 has how many significant figures?

3 sig figs.


(Do not look at the scientific notation when establishing # of sig figs.)

100

In chemistry labs, this unit is most often used to measure volume of liquids.

What is the liter (L)?

100

Which of the following is a chemical change?

a) Evaporation of a puddle of water
b) Melting an ice cube
c) Baking a loaf of bread
d) Freezing water into ice

c) Baking a loaf of bread

New substances form during baking.

100

The subatomic particle that is negatively charged and orbits the nucleus

Electrons

100

The formula for sodium phosphate is:

Na₃PO₄

one phosphate ion (PO₄³⁻), which has a -3 charge, combines with three sodium ions (Na⁺), which each have a +1 charge

200

Use correct # of sig figs.

86.7426 – 17.3 =

69.4

200

If an object has a mass of 27 g and a volume of 9 mL, this is its density.

What is 3.0 g/mL?

200

Which of the following is a physical change?

a) A puddle of water evaporating
b) Iron rusting
c) Gasoline burning
d) Cookies baking

a) A puddle of water evaporating

Evaporation changes state, not composition.

200

The number of these particles determines an atom's identity as an element

Protons

200

The formula for sodium sulfate is:

Na₂SO₄

Na⁺ (charge +1) and SO₄²⁻ (charge –2) combine as Na₂SO₄.

300

use correct # of sig figs.

45.908 m + 12.34215 m + 0.9 m =

59.2 m

300

A temperature of 25 °C equals this many Kelvins.

What is 298 K? (25 + 273)

300

Distinguish between physical and chemical properties 

(find the physical property; the others are chemical properties)

a) The tendency of iron to rust when exposed to oxygen
b) The density of gold
c) The reactivity of sodium with water
d) The ability of hydrogen to burn in air

b) The density of gold

Density is measurable without changing composition. (Study guide topic on physical vs. chemical properties.)

300

Atoms of the same element that have different numbers of neutrons

Isotopes

300

The name of N₂F₂ is:

dinitrogen difluoride

Two N and two F; use prefixes di- and di-

400

A ruler is usually 30 cm long. Express that distance in kilometer. Must use scientific notation.

100 cm = 1 m = 1x10-2 m

1 km = 1000 m = 1x103 m

Answer = 3 x 10-4 km


400

A liquid has a mass of 48.0 g and a volume of 60.0 mL. Express its density in kg/m³.

What is 800 kg/m³?

400

A metal block has a mass of 42.6 g and a volume of 11.3 mL. What is its density?

3.77 g/mL

42.6 / 11.3 ≈ 3.769 → 3.77 g/mL

400

The terms used to describe the weighted average mass of all isotopes of an element based on abundance

Atomic mass/Average atomic mass

400

The name of N₂Cl₂ is:

Two N and two Cl; use prefixes di- and di-

dinitrogen dichloride.

500

An ant travels a distance of 150 mm. Express that distance in kilometers.

1 mm = 0.001 m = 1x10-3 m

1 km = 1000 m =1x103 m

Answer = 1.5x10-4

500

How many cm3 are in 1.000 in3?

1 in = 2.54 cm

Answer: 16.39 cm3

Using 1 in = 2.54 cm, cube the conversion.

1 in3 = (2.54 cm)= 16.387 cm3

500

If a graduated cylinder contains 22.5 mL of water and the volume rises to 75.2 mL after dropping in an object of mass 6.25 g, what is the density of the object?

0.119 g/mL

ΔVolume = 75.2 − 22.5 = 52.7 mL

 6.25 g / 52.7 mL ≈ 0.1186 → 0.119 g/mL.

500

Carbon-14 and Carbon-12 are isotopes. The difference between these is the number of...

Neutrons

500

What is the formula when Na⁺ combines with PO₄³⁻?

Na₃PO₄

Three Na⁺ needed to balance one PO₄³⁻